It has been known to three-dimensionally displaying a combination of images to provide stereoscopic viewing with utilizing a disparity between the images. Such stereoscopic viewing can be achieved by taking more than one images of the same subject with more than one cameras placed at different positions, and three-dimensionally displaying the images with utilizing a disparity between the subject images contained in the images.
Specifically, if the stereoscopic viewing is achieved by parallel viewing with naked eyes, the three-dimensional display can be achieved by arranging the images side by side. Further, the three-dimensional display may be achieved by combining images, for example, by overlapping the images with changing the colors of the images, such as into red and blue, or by overlapping the images with providing different polarization directions of the images. In these cases, the stereoscopic viewing can be achieved by using image separating glasses, such as red-and-blue glasses or polarization glasses, to provide a merged view of the images displayed for three-dimensional viewing attained via the automatic focusing function of the eyes (anaglyph system, polarization filter system).
Furthermore, the stereoscopic viewing may be achieved by displaying images on a three-dimensional display monitor which allow the stereoscopic viewing, such as of a parallax barrier system or a lenticular system, without using polarization glasses, etc. In this case, the three-dimensional display is achieved by alternately arranging vertical strips of the images. Moreover, a method for providing three-dimensional display by alternately displaying left and right images with changing directions of light beams from the left and right images through the use of image separation glasses or attaching an optical element on the liquid crystal display has bee proposed (scanning backlight system).
In addition, a polynocular camera including more than one imaging units for taking images for the above-described three-dimensional display has been proposed. Such a polynocular camera includes a three-dimensional display monitor, and generates a three-dimensional image for three-dimensional display from the images acquired with the imaging units. The generated three-dimensional image can be displayed for three-dimensional viewing on the three-dimensional display monitor.
The images used for the three-dimensional display are obtained by photographing a subject from different points of view, and therefore each image contains an area at the end portion thereof which is not contained in the other image. For example, in a case where the three-dimensional display is carried out using two images G1 and G2 as shown in FIG. 22, an area A51 in the image G1 is not present in the image G2, and an area A52 in the image G2 is not present in the image G1. When such images are displayed for three-dimensional viewing, even if the person at the end portion of each image is to appear to pop forward from the display surface, the stereoscopic effect of the person abruptly vanishes at the left end portion of the three-dimensional image and the left half of the person is displayed two-dimensionally, since a part of the person is not present in the image G2. This results in very unnatural appearance at the end portion of the three-dimensional image.
In order to address this problem, a method has been proposed, in which, when one of the images contains complete information of an object, which appears to pop forward when stereoscopically viewed, and the other of the images does not contain complete information of the object, and thus the three-dimensional display cannot be achieved, the one of the images is masked, for example, to remove a part of the information of the object, thereby achieving the three-dimensional display (see Japanese Unexamined Patent Publication No. 8 (1996)-065715, which is hereinafter referred to as patent document 1). Another method has been proposed, which changes the stereoscopic effect of objects when images containing more than one objects are displayed for three-dimensional viewing (see Japanese Unexamined Patent Publication No. 2005-065162, which is hereinafter referred to as patent document 2).
In the method disclosed in patent document 1, however, although the situation where the object cannot be displayed for three-dimensional viewing is resolved, this method is effective only on a particular object, and the stereoscopic effect of other objects, which are present in front of or at the rear of the particular object, abruptly vanishes. Thus, if the three-dimensional image has a stereoscopic effect with which the image appears to pop forward from the display surface, the observer who views the image feels that the three-dimensional image is very unnatural.